Elevated Levels of Hormone Linked to Increased Risk of Stillbirth and Placenta Abnormalities
Dec. 29, 1999 (New York) -- Some women who deliver stillborn babies may have detectable elevations of a hormone in their blood during the second trimester of pregnancy, according to a study published in the Dec. 30 issue of The New England Journal of Medicine. However, the association between the elevated hormone levels and the risk of stillbirth is too small to recommend that all women with elevated levels be treated as a precaution.
The authors also found an association between high levels of the hormone, called serum chorionic gonadotropin, and various abnormalities of the placenta. However, they conclude that it would be necessary to overtreat hundreds of women in order to prevent just one stillbirth, assuming that there is a treatment that would be of value.
Chorionic gonadotropin is one of the tests that are commonly used at 15 to 20 weeks of pregnancy to check for abnormalities such as Down's syndrome. Some studies have suggested that high levels of chorionic gonadotropin are predictive of serious pregnancy complications -- however, the definition for what constitutes "high" blood levels of chorionic gonadotropin concentrations ranges from two to five times the normal level.
In the study, which included data on nearly 30,000 pregnancies in girls and women ages 10 to 44, 2,561 women had chorionic gonadotropin levels that were at least two times the normal level, but only 79 women had stillbirths, for an overall stillbirth rate of 2.8 per 1,000 pregnancies. The rate of stillbirth was substantially higher for blacks, Filipinos, and Pacific Islanders, as well as girls and women of races or ethnic groups categorized as 'other' or 'unknown.' The rates of stillbirth among these women ranged from four to seven per 1,000 compared with less than two per 1,000 for white women.
The authors of the new study, from the Kaiser Permanente Medical Care Program in Oakland, Calif., also say not only would an arbitrary cutoff such as two times the normal level lead to overtreating many women, it could have the potential to cause anxiety and stress for pregnant women who are not at increased risk of stillbirth but happen to have slightly elevated levels of the hormone.
"These psychological effects can persist and may lead to a negative attitude toward the pregnancy and the baby," Walton and colleagues write. In addition, there is no evidence to indicate that an effective, low-risk treatment for women with high levels will prevent a stillbirth.
As a stand-alone test for predicting stillbirth or other complications, chorionic gonadotropin elevations are of little value, but its sensitivity and predictive value increase when used in combination with assessment of other risk factors such as socioeconomic status, race or ethnic background, reproductive history, and biochemical and biophysical markers, says David A. Luthy, MD, in an editorial accompanying the study.
"Once a high-risk group is identified, however, the question remains whether careful monitoring and timely interventions will improve the outcome of pregnancy," writes Luthy, of the Obstetrix Medical Group in Seattle. "Unfortunately, there is little evidence to date that they will."
Walton and colleagues conclude that high values of chorionic gonadotropin may serve to alert physicians to possible placenta-related problems and consequently, lead to earlier detection, but they agree with Luthy that it is unknown how this knowledge ultimately will affect the outcome of the pregnancy.